[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 231451
TCDAT1

Tropical Storm Ophelia Discussion Number   9
NWS National Hurricane Center Miami FL       AL162023
1100 AM EDT Sat Sep 23 2023

Since Ophelia made landfall earlier this morning, the tropical storm
has maintained a healthy appearance in radar reflectivity from both
the Morehead City and Raleigh radars, though the Doppler wind
velocities have steadily decreased as it moves further inland.
1-minute GOES-16 visible imagery depicts curved banding near the
center of Ophelia, though the coldest cloud tops on infrared imagery
have warmed from last night. The Doppler velocity data and surface
observations suggest that maximum sustained winds are down to 45 kt
this advisory, though this could be somewhat generous. However,
Ophelia continues to produce a large swath of heavy rainfall both
near and north of the current storm position, where a large region
of Flood Watches and Warnings remain in effect.

The tropical storm appears to have accelerated this morning, with
the latest estimated motion at 355/11 kt. Over the next 12-24 hours,
Ophelia is expected to begin turning northeastward as it moves into
southeastern Virginia by this evening. This motion should slow a bit
as it becomes tangled up in a frontal boundary moving into the
Delmarva Peninsula and off the mid-Atlantic coastline on Sunday. The
track forecast this cycle is quite similar to the prior advisory, in
best agreement with the simple and corrected track guidance.

Continued weakening is expected as Ophelia continues to move inland
across eastern North Carolina and then southeastern Virginia. On
Sunday, Ophelia's circulation is forecast to become increasingly
elongated as interacts with a pre-existing frontal boundary offshore
of the Mid-Atlantic coastline. Most of the model guidance shows
Ophelia merging with the baroclinic zone in about 24 hours, marking
its transition to an extratropical cyclone, with the low ultimately
being absorbed by the frontal zone in 48-60 h, though this could
occur sooner.

Key Messages:

1. Tropical storm conditions will continue along portions of the
southeastern and mid-Atlantic U.S. coasts within the Tropical Storm
Warning area today.

2. There is a danger of life-threatening storm surge inundation
over portions of eastern North Carolina and southeastern Virginia,
including Pamlico and Albemarle Sounds, the Neuse and Pamlico
Rivers, the lower James River, and the lower Chesapeake Bay, where
Storm Surge Warnings are in place.  Residents in these areas should
follow advice given by local officials.

3. Heavy rainfall from Ophelia may produce locally considerable
flash, and urban flooding impacts across portions of the
Mid-Atlantic states from North Carolina to New Jersey through
Sunday.

4. Swells generated by this system will affect much of the U.S.
east coast through the weekend, likely causing life-threatening
surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 35.6N  77.2W   45 KT  50 MPH
 12H  24/0000Z 36.8N  77.3W   35 KT  40 MPH...INLAND
 24H  24/1200Z 38.2N  76.6W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  25/0000Z 39.1N  75.1W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  25/1200Z 39.3N  73.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
 60H  26/0000Z...DISSIPATED

$$
Forecaster Papin
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